Problem: If $3a + b + 5c = 1$ and $6x + 2y = 7$, what is $-27a - 9b - 16y - 45c - 48x$ ?
Solution: $= -27a - 9b - 45c - 48x - 16y$ $= (-9) \cdot (3a + b + 5c) + (-8) \cdot (6x + 2y)$ $= (-9) \cdot (1) + (-8) \cdot (7)$ $= -9 - 56$ $= -65$